1. Field of the Invention
The present invention relates to optical devices. More specifically, the present invention relates to optical rotators.
2. Description of the Related Art
For optical systems, there is often a need to rotate the polarization state of an optical beam. For this purpose, optical rotators are made of quartz are often used. A half waveplate made of birefringent material can also be employed to transform a given linear polarization state into a different linear polarization state. A specific orientation of the half waveplate is necessary to achieve this result, while the optical rotator can have any orientation. These devices are generally passive and reciprocal. Electro-optical crystals are active waveplates, where phase is proportional to applied voltage. Non-reciprocal applications require Faraday rotators.
An optically active rotator rotates the plane of polarization of light passing through it. A typical optically active rotator is generally a fairly long device, requiring a large block of optical grade material such as quartz. One of the advantages of an optically active medium used in fabricating a rotator is that the rotator can be fabricated that rotates the transmitted beam by any desired angle, not just 90.degree.. One of the disadvantages to employing an optically active medium is that high quality material is not available at all wavelengths.
Other inventions by this Applicant also assigned to Raytheon Company include:
"Reeder Rod" Ser. No. 09/482,230, filed Jan. 13, 2000; "Reeder Compensator" Ser. No. 09/482,376, filed Jan. 13, 2000; and "Waveplate Polarization Rotator" Ser. No. 09/482,378, filed Jan. 13, 2000; These applications are incorporated herein by reference.
Thus, there is a need in the art for a rotator which is much thinner than an equivalent 90.degree. quartz rotator using much less optical grade material. There is a Other need for a rotator would be made of any uniformly birefringent medium. This would extend the possible wavelength range of operation as optically active rotators are not currently available at all wavelengths.